• Journal of the Korean Institute of Gas
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• v.22 no.2
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• pp.59-66
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• 2018

Using hydrogen fuel is expected to be suitable as a reciprocating internal combustion engine with heightened interest in HALE(High Altitude Long Endurance) UAV(Unmanned Aerial Vehicle). Hydrogen is hightest energy density per mass so it can continue to charge for long periods of time and have positive part of the environmental effects. However, it is estimated that there is less research on hydrogen fuel engine currently applied, and many studies need to be done. Depending on the operation, there are factors that result in supercooling due to reduced radiation or reduce cooling performance due to low air density. Therefore, the experiment was to change the temperature of the cooling water and investigate the effect on engine combustions. The limitation of the stable operation range due to backfire is dominated by the excess air ratio rather than the effect of the cooling water temperature change. When the cooling water temperature increases, the volumetric efficiency decreases and the torque decreases. As the cooling water temperature decreases, the heat loss was increased and consequently the thermal efficiency was decreased.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.3
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• pp.289-300
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• 2013

This study numerically considered the characteristic of smoke movement and the effect of hot smoke gas on tunnel wall surface temperature during road tunnel fire under boundary condition of fire growth curve that is applied to fire analysis in road tunnels. The maximum heat release rate were 20 MW and 100 MW and tunnel air velocities were 2.5 m/s and velocity induced by thermal buoyancy respectively, also the cooling effect of tunnel wall was considered. As results, when tunnel air velocity was constant at 2.5 m/s during tunnel fire, due to the cooling effect of tunnel wall, the smoke layer was rapidly descent after some distance and it flowed the same patterns at the downstream. When heat release rate was 100 MW (and jet fan was not installed), the maximum temperature of tunnel wall surface has risen up to $615^{\circ}C$. The heat transfer coefficient of tunnel wall surface was varied from 13 to $23W/m^2^{\circ}C$ approximately.

• Asian Journal of Turfgrass Science
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• v.17 no.2_3
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• pp.67-73
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• 2003

A series of studies was conducted during 2 years to investigate the effect of transplanting time and turfgrass species on turf establishment rate of sod for 2002 World Cup Soccer ground construction. The required period of rooting and turf growth for acceptable soccer playing quality on transplanted sod from nursery was tested to collect data for the project authorities of hosting cities and construction companies who were involved in World Cup stadium project. Transplanting time significantly affects on rooting-potential of sod on cool season grass and zoysiagrass, but those effects differently showed by turfgrass species. The enough nursing period for the ground established by Zousiagrass should be secured with proper transplanting time. And the thermal insulation on the turf canopy with other maintenance during Winter should improve the early rooting on zoysiagrass. The sod contained Kentucky bluegrass (85％＋15％ perennial ryegrass, seed wt. basis) showed relatively slow at the early growth and rooting-potential of root, but the potential resulted higher than that of perennial ryegrass turf (85％＋15％ Kentucky) under longer nursing period. Kentucky bluegrass has one of the most strong resistance against environmental stresses, but intensive maintenance practise should be required when the turf transplanted during summer season. Higher mixture rate of perennial ryegrass sod has a rapid root growth compare with other turfgrass species. The rate provided a benefit to an early establishment of turf ground followed by a proper maintenance practise. For the completion of World Cup soccer ground construction for 2002, the most suitable time for sod transplanting in 2001 was March to May or mid Sept. to early Oct. by delayed architect construction schedule.

• Applied Biological Chemistry
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• v.48 no.1
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• pp.103-108
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• 2005

${\alpha}-Amylase$ inhibitor is used to control blood glucose level by inhibiting starch digestion in the small intestine and delaying the absorption of glucose. In this study, we investigated the effect of the ethanol extracts from more than 1400 species of plants against ${\alpha}-amylase$ with the aim of developing a new ${\alpha}-amylase$ inhibitor. In the results, Cornus walteri extracts showed the highest inhibition activity. The inhibitory effect of Cornus walteri extract on the carbohydrate hydrolysis enzymes has different sensitivities against ${\alpha}-amylase$ from salivary and pancreatin and against ${\alpha}-glucosidase$ from yeast and porcine small intestine. In the study of inhibition kinetics of ${\alpha}-amylase$ and ${\alpha}-glucosidase$, Cornus walteri extract showed competitive inhibition against salivary and pancreatin while showing the combination of uncompetitive and noncompetitive inhibition against ${\alpha}-glucosidase$. The Cornus walteri extract was stable at acidic and thermal conditions. As for the blood glucose and body weight levels of Cornus walteri extract, we confirmed anti-hyperglycemic and anti-obesity effects. Also, in the investigation of the mRNA lever, Cornus walteri extract upregulated the level of GLUT4 mRNA in the quadriceps muscle.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.11
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• pp.636-641
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• 2015

Waste energy conversion to SRF (Solid Refuse Fuel) has the effects not alternative fossil fuel usage but also the reduction of greenhouse gas. But the direct burning of the SRF including a plastic waste generates air pollution problem like soot, dioxin, etc. so that an application of pyrolysis and gasification treatment should be needed. The purpose of this study is to supply a basic thermal data of the pyrolysis gasification characteristics in the plastic-rich SRF which are needed for developing the novel pyrolyser or gasifier. To do so, a bench-scale test rig was newly engineered, and then experiments were achieved for the production characteristics of gas, tar, and char. While SRF sample, gasification air ratio, holding time changed as 2 g, 0.691, 32 min respectively, the $H_2$ 1.36%, $CH_4$ 2.18%, CO 1.88%, $Cl_2$ 15.9 ppm, HCl 6.4 ppm were composed. Also light tar benzene $4.03g/m^3$, naphthalene $0.39g/m^3$, anthracene $0.11g/m^3$, pyrene $0.06g/m^3$, gravimetric tar $18g/m^3$, and char 0.29 g was formed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.1
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• pp.71-76
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• 2002

To understand the effect of heated effluent from a nuclear power plant on marine organism, experimental culture of Halocynthia roretzi was carried out at heated effluent of Wolsung nuclear power plant from January to December 1996. Temperature was $11.2\~27.9^{\circ}C$ and salinity was $32.54\~34.59\%_{\circ}$ during the culture period, The Growth of H. roretzi on lower area of Bonggil-ri (St. 1) was not normal in height, breadth and weight due to heated effluent. Daily growth rate (DGR) of H. roretzi about Kampo area (St, 4) was significant other station, and St. 1 was significant from other station except St. 4, Mytilus edulis was major fouling organism (over $90\%$) that were M. edulis, Dideninum moseleyi, Styela clava in experiment culture farm. St. 1 was higher (mean 143 individual) and St. 4 was lower (mean 56 individual) appearance attached of M. edulis. Growth of H. roretzi reduced when attached number of M. eduiis was increased, because correlation between DGR and number of M. edulis was negative.

• Journal of Navigation and Port Research
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• v.36 no.6
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• pp.459-463
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• 2012

In the present study, experiments have been performed to investigate the effects of the type of adsorbent, pH, and ionic strength on the adsorption of nutrients (nitrate and phosphate in artificial solution) onto the dredged sediment from a coastal fishery. In addition, this study aims to evaluate the possibility of removing the nutrients from the water using the dredged sediment. In the adsorption experiments of the nutrients, the reactions were completed within 10 minutes using ${NO_3}^-$-N($100{\mu}M$, 10mM) and ${PO_4}^{3-}$-P($100{\mu}M$, 10mM). In the steady state, 61% and 77% of the initial amounts were removed respectively for $100{\mu}M$ ${NO_3}^-$-N and $100{\mu}M$ ${PO_4}^{3-}$-P. The thermal treatment of the dredged sediment at $900^{\circ}C$ was not helpful to increase the removal efficiencies of the nutrients. Additives such as CaO and MgO dropped the removal efficiency of ${NO_3}^-$ to 0%, but increased that of ${PO_4}^{3-}$ up to 98%. Adsorption isotherms of ${NO_3}^-$ and ${PO_4}^{3-}$ could be explained by the Freundlich equation ($R^2$>0.99). The adsorption reaction was little influenced by the pH and ionic strength. Based on the results showing short reaction time and considerably high removal efficiencies of the nutrients, it is proposed to apply the dredged sediment from a coastal fishery to removing nutrients such as nitrate and phosphate in the water.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.476-481
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• 2016

Steam power generation is used to produce electricity through a generator that is connected to a steam turbine. As a result, the surface temperature of the deaerator is $70^{\circ}C$during the summer season, the surface temperature of the storage tank is $67^{\circ}C$, and the air temperature is $50^{\circ}C$. This environment is inappropriate for workers and instruments. Workers adjacent to the deaerator and storage tank in particular feel higher temperatures because of the radiative heat transfer effect. Therefore, we optimized the cooling conditions by computational analysis. Case 1 is the current shape of the power plant, Case 2 has additional insulation, and Case 3 has a radiation shield. Flow is caused by a temperature difference between the heat sources in the wall, and hot air is trapped in the right upper end. Based on the temperature contours and the maximum temperature of the surfaces, Case 2 was found to be the most efficient for reducing radiative heat transfer effects.

• Resources Recycling
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• v.27 no.1
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• pp.45-54
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• 2018

This study aimed to investigate the effects of mechanical factors such as agitation speed and air rate in fly ash flotation. Specifically, we used thermal power plant fly ash with unburned carbon content of 3.4 to 3.7%. The effect of pH, agitation speed, collector dosage, and frother dosage - the key factors of froth flotation - showed unburned carbon recovery and unburned carbon content of 63% and 34%, respectively, when the dosage of safflower oil used as collector was 800 g/ton, pH was 7, agitation speed was 1,200 rpm, and frother dosage was 400 g/ton. The SEM/EDS analysis of fly ash in that case indicated that the spherical fly ash particles lowered the unburned carbon content as they floated with the air bubbles without being dissolved in the unburned carbon or settled in the ore solution. The other experiment of changing the mechanical factors such as agitation speed and air rate resulted in unburned carbon recovery and unburned carbon content of 74% and 67%, respectively, at air rate of 8 L/min and agitation speed of 900 rpm. The recovery and unburned carbon content increased as the low agitation speed and additional air injection decreased the strength of the eddy current in the ore solution and consequently prevented the floating of fine fly ash particles with unburned carbon. In addition, the recovery rate and unburned carbon increased further to 80% and 70%, respectively, showing the best performance when the agitation speed and air rate were lowered to 800 rpm and 6 L/min, respectively.

• Elastomers and Composites
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• v.34 no.3
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• pp.199-211
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• 1999

In this work, the effects of the addition of epoxy on the properties of PVC-sol sealants were investigated. PVC-sol was plasticized with dioctyl phthalates(DOP). Two kinds of epoxy resins having different epoxy equivalent weight (E.E.W.) were used. It was found that the properties of the PVC-sol sealants were significantly affected by the contents and types of the added epoxy resins. The viscosity behaviors of the epoxy-modified sealants, in the case of epoxy A addition, the viscosity was decreased with increasing the epoxy contents, but In the case of $CaCO_3$ addition, the viscosity was increased with increasing the $CaCO_3$ contents. The viscosity of epoxy modified sealants aged at $45^{\circ}C$ waterbath was decreased with increasing epoxy contents, since the epoxy acted on the sealants as a stabilizer. The thermal stability of the PVC-sol sealants was slightly improved by adding epoxy. The tensile strength and elongation of sealants modified with epoxy A(two functionalities of epoxy) were increased with increasing the epoxy contents up to a certain epoxy contents but was decreased with further increasing the epoxy contents. In the case of $CaCO_3$ addition, the tensile strength of sealants were decreased with increasing the $CaCO_3$ contents. In view of the electrical properties, such as tan ${\delta}$($0.1{\pm}0.04$) and ${\epsilon}_r$($0.5{\pm}0.04$), it was found that the epoxy modified sealants were as good as insulators.